Wilhelm schmidt



(No Model.)

`.2 Sheets-Sheet 1.

Patented Sept. 30, 1884.

W. SCHMIDT.

CUT-OPP SLIDE VALVE.

(No Model.) 2 Sheets-Sheet 2.

W. SCHMIDT.

GUT-UFP SLIDE VALVE.

No. 365,762. Patented se E t. 30, 1884. l!

\\\\\`\\\3' \\\w .vl-\v Iinrrn raras VIIiI-IELH SCHMIDT, OF BRUNSWICK, GRAND DUCHY OF BRUNSVICK,

GERMANY.

CUT-OFF SLIDE-VALVE.

PECIFICATION forming part of Letters Patent No. 305,762, dated September 30, 1884-.

Application tiled April 2, 1R84. `(No model.)

To, m7/ 'wh/0m, it may concern:

3c it known that I, WILHELM ScHMinr, of the city of Brunswick, Grand Duchy of Brunswick, German Empire, have invented anew and useful Improvement in Cut-Off Slide- Valves, of which the following is a full, clear, and exact specification.

This invention relates to slide-valves for steam, gas, and other fluid-pressure engines. rIhe improved valve has the peculiar feature that the expansion-valveis moved direct-by an eceentric,while the main valve has no positive motion, but is periodically moved by the admission and exhausting of steam between the valves.

In further describing the invention reference will be made to the accompanying drawings, Figures I to VII, which show two different arrar gements of slide-valves embodying this in'- vention. Fig. I is a longitudinal vertical section, Fig. II a cross-section, and Fig. III a horizontal section, of a valve-chest. Fig. IV shows alongitudinal section and plan ofa modiiication, and FigsV to VII are diagrams showand valves, and serving to explain their function. rlhe corresponding position ofthe crank and eccentric is indicated at the side of these figures.

rlhe main valve g, Figs. I and II, is similar to an ordinary slide-valve having three steamports, ct l) c, adapted to periodically communicate with the steam-ports c b c of the cylinder. The exlnmsion-valve m has in its base recesses o o,which form,with the recesses lr ff", asort of hollow frame. The main-valve g, which may have similar recesses, contains two perforations, sA s', extending from its base to its upper side across the ports a and c. For securing or arresting t-he freely-movable main valve g when the engine runs light two weak springs, f j", maybe employed.

The mode of operation is as follows: In the position corresponding to Fig. Ithe engine-piston is at the right end of its stroke, (see Fig. VQ and the space K of the cylinder communicates with the exhaust-port b, leading into the atmosphere or to the condenser;l but thc con.- denser also produces a diminution of pressure 5p in the recess o of the expansion-valve, so that the latter is firmly coupled with the main valve by the pressure ofsteam on the back ofthe valve m. The main valve g will be dragged with the eXpansion-valvem as long as the recess o (and consequently also o) remains closed against the interior of the valve-chest; but as soon as the port a communicates at its lower end with the steam-space of the valve-chest, Fig. TI, the pressure on the top of the valve is balanced by the pressure from below, the connection between the twovalves ceases and the lower valve, g, remains stationary, while the upper valve continues its motion to the end of its stroke. (See Fig. VII.) In this position the recess o communicates already with the port c' through the port c, and therefore with the expanded steam in the steam-cylinder. XVhen the valve commences its motion to the right, the pressure in the recesses is already sufficiently low to cause a suction or coupling action between the two valves, in consequence of which the lower valve will be dragged along until the port c communicates bolowwith the steam-space of the valve-chest, which terminates the connection between the two val ves. It is evident that ing the relative position of the engine-piston i the valves would also work without the perforations or auxiliary portss s',- but these ports are advantageous, inasmuch as any vapors which may pass between the twovalvcs through leakage will escape, and thereby insuring a perfeet working ofthe valves. These recesses may be employed in various expansion-valves. If the expansion-valve m is made in two parts. the recesses o o must be made separately in each part of the same, and connected with each other by a U-shaped canal, t, provided in the main valve, as shown in dotted lines on Fig. I.

FigIV shows a modification ofthe improvedy valve, in which the ports s s', serving to temporarily take up any steam escaped through leakage, are not in communication with the steam-ports a c', but with the exhaust-port b', which communication is mai n tained during the motion of the valve. For this purpose, notches a n" are provided in the valve-face of the cylinder, and projections z t" aie adapted to effect the coupling and uncoupling of the valves in a manner analogous to that described in Fig. I.`

In the position represented by the drawings the exhaust from between the valves takes place through the exhaust-port b', recess n', duct s', and recess o. The coupled valves move to- IOC) ward the left until the edge 3 has passed over the left-hand edge2 ofthe valve-face of the cylinder, whereupon the connection between the valves ceases. The expansion-valve continues to move until the end of its stroke, in which position the lower valve is again moved with the upper one, because the recess o communicates With the duct s. At this moment the latter terminates in the port a', and as the latter is not covered along its whole Width by the part c, the port ca will also communicate with the exhaust-port b.

What I claim isl. A pair ofslide-Valves adapted to slide upy on each otherfand provided at their contactg surface with recesses adapted to periodically communicate with the exhaust-space or eX- haust-port of the engine, for the purpose of reducing the pressure between the said valves and causing them to move together, substantially as described.

2. The combination of a main valve having auxiliary ducts s s', crossing the main ports a c, with an expansion-valve adapted to slide on the back of the main valve, the contaetsurface of 2 5 one or both of the valves being provided with recesses o o, communicating with the du cts s s. substantially as and for the purpose described.

The foregoing specication of my improvement in slides for engines and machines signed 3o by me this 20th day of December, 1883.

WILHELM SCHMIDT.

Vitnesses:

B. Roi, A. KUHNT. 

